Three-wire multiple system.



No: 874,147. PATENTED DEC. 17, 1907.

v 0. s. WINSTON.

THREE WIRE MULTIPLE SYSTEM.

APPLICATION FILED MAR. 12, 1906.

I a citizen of the United UNITED sTArEs PATENT OFFICE.

eHAsLEs s. WINSTQN, or CHICAGO, ILLINOIS, ASSIGNOR T -KELLOGG SWITCHBOARD &

SUPPLY COMPANY, or omeAeo, ILLINOIS, A CORPORATION or ILLINOIS.

. THREE-WIRE MULTIPLE sYs'rEir.

Specification of Letters Patent.

Patented Dee.17,1907.

Application filadlarch 12, 1906. 8orial No. 305.512.

To all whom it may concern; Be it known'that 1, CHARLES S. Wms'ro'N, States of1Amen-sa, andresident of Chicago, county of Cook, andv State of Illinois, have invented a new and, useful Improvement in Three-Wire Multiple Systems, of which the following is a specification. I v f My invention relates to a common battery telephone system' of the type known as three-wire systems in'wlnch two wires or tend throughout the multiple of the switchboard section of the lines for" talking. pur-' 8 in (a bridge of said conductors normallyposes, and a third wireis provided for testing and signaling purposes. v

My objectis to general type embodying a simplified circuit arrangement and in which a positive and effiemnt operation of the signals between the subscrlbers stations and the central office is secured.

I have shown one embodiment 011113 111- drawmg in extending to the central line conductors 3 and 4.

I have indicated. the subscribers appara-:

tus as consisting of a call bell 5 and, condenser 6 in a normally-closed-brid'ge of the line conductors and'a transmitter .7 and receiver 1 open. at the switch book 9 when the subbeing connected to 'of the jacks is scribers telephone is in use. I At the central office thelineieonductor, 3

terminates in the ti .-jack spring 10 andisoneslde of the windermanently secure to I mg" 11 of the line relay, the opposite-side of said winding being connected with the central oflice battery 12 13. Line conductor 4 terminates in the sleeve jack spring 14, said line conductor being also connectedwith one side of the winding 15'of the line relay, the opposite connected by means-of conductor 16 an" the normallyclosed contacts 17 of the cut-off relay 18 to the grounded side of the central office battery. A third contact or testing terminal 19 connected by means of conductor 20 with cut-off relay, the other side of said winding central oflice battery. The jack contacts of each line are multipled'at the different sections of-the switchboard as shown. A commally'open at the produce a system of this side of the condenser tween the non-grounded side of '12jand the third contact of the answering bymeans of conductor the listening key ringing key 43 18 adapted to bridge the ringdesired subscriber.

one side of the-winding of the the grounded side of the tacts 17 of the cut-ofi rela ed side of the battery.

paratively low resistance coil 21 is connected between the testing terminal '19 of the jacks and the grounded side of the battery through the normally-closed back contacts 22 of the line relay. A line si nal 23 has its circuit normally open at the irontcontact 24 of the line relay and normally closed at the back contact 25 of the cut-off relay, said-signal being ductor'26 when the line relay is energized.

The operators cord circuit. consists of a .tip strand 27 having an interposedcondenser.

adapted to receivevdi rrent over con- 28 and a; sleeve strand 29 having art/intent.-

posed condenser 30; The tip strandis norfront contact 31 of the rela 32, the normallyl closed contact 33 of said re ay connecting t listening key 36, with a tertiary winding 37 The relay 32 is connected between the grounded side of the battery 12 and the sleeve strand of the. cord circuit upon one e calling end of the tip strand, by means of conductor 34, and the normally-open contact carried upon the f of the operators induction c'oil, the opposite side of said coil-being connected with ground.

30 and, an impedance coil 38 is eonnected'between the grounded side of the battery. and the sleevestrand of the cord circuitupon the opposite side of said condenser.

A supervisory signal 39-is connected bethe battery in the operation of moval of t e receiver from the telephone hook at. station 1 would permit a flow of current from the battery 12 over conductor 13, winding 11 of the line relay, the limbs of the -telephone line including the substation apparatus, winding 15 of the line relay, conductor 16, and the normally-closed con- 18 to the groundhe coilsllfand 15 ead telephone,

bridged across 'ioo the system, the re- 7 trac ted to closethe circuit of the line signal 23 at thefront contact 24 of saidrel'ay. The

of the line relay are wound in the same div,frection so that their magnetic mfiuenoe 18 of said relay is atadded, and the armature e calgling'line. Current will then flow from the battery 12 over. conductor 40 through the supe' visory signal 39, testing terminal 19, con uctor "and the winding of the cut-off relay 18 to battery. The cutoff relay is of suflicicntly high resistance-to iprevent the supervisory signal obtalnin sutcient current over this path for its 1lum1- nation. It will be noted that the low resistcircuit of thedine lampl a'nce shunt 21, is open at the contacts of the line relay and all the current is obliged to pass through the winding of the cut-ofi relay, which is operated and attracts its armatures, removing the ground connection from the winding15 of the line relay at its nor-- inally-closed contacts 17, and opening the r 23 at its n( 1;mally closed 'contacts 25. '1 e line signal is thus eilaced, and the impedance 38 is substituted in the sleeve side of the line in place of the coil 15 ofthe line relay. The balanced conditionof the circuit is therefore not disturbedby thepperation of thecut-ofl relay. The

coil 11 is, however, suflicient to maintain the line-relay actuated as long as the subscribers receiver is in use, preventing connection with the low resistance shunt 21, and the supervisory signal 39 remains dark. The current previous y flowin through coil 15 of the line relay now flows om line conductor 4, over the sleeve contacts of the plug and jack,

sleeve strand 29 of the cord circuit, and the I impedance coil 38 to thev grounded side of the batter The operatorthe calling sub-.

winding of the may now communicate wit 1 scriber b bridging her telephone set across the line y said operation connecting the tertiary winding 37. of her inductioncoil with the tip of thecalling plug by means of the normallyen contact 35 carried by the listening ke pon ascertaining the number of,the s'u scriber desired .the operator will test the con dition of the line in-the usual .manner by touching the ti of her calling plu 'to the testing termina 19 of the desired line. If the line is busy a potentialabove" that of ground will exist upon the sleeve of the line tested which will produce a flow of current 0ver 't1e tip strand of .thecord circuit to conductor 34, contact 35, the listening key being thrown, and the tertiar winding 37 of the operators induction coi to ground, producmg an inductive click in the ,operators head receiver and notifying her that the line is 26 and contacts 25 r w tacts 'carried by her of one of her cord circuits in path in sleevecontacts of the means 'of the listening key 36,

busy.' If no connection exists with the dcsired line at any of the other switchboard ,sections,, .,-tlie testing terminals of said line.

will be connected to ounl through the winding of the cut-off relay, and the operators testing strand being also connected, with ground through the normally-open con-. listening key, no flow of current will result. I Upon finding the lineidle the o erator will insert her calling plu into the jac of the desired hne, causing a ow of current from the battery 12 over conductor 42, supervisory signal '41, testin terminal 19' of the jack, conductor 20an the winding of the cut-ol relay 18 to ground, which will attract its armature, opening the circuit of the line lamp 23, and removing the ground connection from the-winding 15 of the line relay. Due

to the fact that the telephone receiver of the called subscriber is upon'its hook, no flow of current will result through the winding 11 of the line relay, and the comparatively low resistance path 21 will be connected with ground, in parallel with the winding of thc cut-oil r'elay,'at the normally closed contact 22 of the line relay. This low resistance arallel with the cut-oil relay, will permit tie supervisory lamp 41 to receive sufiicient current forits illumination, thus notifying the operator of the condition of the sub-statlon apparatus. The operator will now connect the ringing generator with the sleeve side of the line to signal the subscriber,

current flowing from said generator to the plug and jack, line conductor 4, substation line conductor 3, ti coptacts of the ack and plug and back to the 'enerator through the grounded contacts of t 1e ringing key. Upon the response of the called subscriber a path for current is completed from the battery 12 over conductor 13, the winding 11 of the line relay, line conductor 3, the sub-station apparatus, line conductor 4, 'aek sleeve contact 14, the sleeve strand of t e cord circuit, and the windin of the relay 32 to the battery. The flow 0 current in this ath will cause the operation of the line .relity, which will olpen the circuit of the low resistance-21at t e normally-closedback contact of said relay, thus extinguishing the supervisor sig-' nal 41, said signal not receivin sufiicient current throu h the winding of the high resistance cut-o 'r'elay 18 to cause its illumination. The rela 32 is also operated by current in this pat severin tween the calling end or conductor 34, and unitin the normally severed parts of said stran .for conversation. The subscribers are now in communication the tip strand and for conversation. The impedance of the windings 11- of the linerelayst and the coils 32 and 33, prevent shunting of the volce currents, said currents being inductively comsignaling apparatus,

the connection be- 'municated from one side of the cord circuit to the other by means of the condensers 28 and 30. Each subscriber by'replacing his receiver upon the hook will interrupt the flow of current through thewinding 11 of the line,

, relay, permitting its armature to drop back '1 and inserting the low resistance 21 in parallel with the winding of the cut-off relay, thus permitting suflicient current to 'fiow through the associated supervisory signal to illuminate the same, indicating to the 0 eratoi' that the conversation has terminate The removal of the plugs from the jacks restores all arts to normal condition.

lghat I claim is: 1. In a telephone system, the combination with a pair of telephone lines', of a cord,

circuit for making connection therewitli for conversation, a line relay permanently con nected with the line, a 'thirdbonductor] at the central office, a cut-ofl' relay permanently connected with said third conductor and controlling contacts normally in the circuit of theline, a supervisorysignal in said third conductor associated with the cord circuit, and a low resistance path in parallel with the portion of said conductor associated with the' line, said 1 supervisory signal receiving ins'u fiicient current for its operation when 'sa1d low TG'SlStitIifJG path is 0 en, said path being closed at the contacts 0 said line relay when the subscribers telephone is not in use and a connectionexists with the line, whereby said signal is operated, substantially as described,

2. In a tele hone system, the combination with a pair 0 telephone lines, of a cord circuit for making connection therewith for conversation, a ine relay ermanently connected with the line, a thir conductor at the central ofiice, a cut-off relay permanently connected with said third conductor and controlling contacts in the circuit of the line, a signal for the line having its circuit jointly controlled by the contacts of said relays, a supervisory s' al in said third conductor associated wit the cord circuit, and a low resistance path in. parallel with the ortion of said conductor associated with t e line,

.said supervisorysignal receiving insufficient current for its operatron when said low res tance-path is open, said path be' n closed at the contacts of said line relay w en the subscribers telephone is not in use and a connection exists with the line, whereby said signal is operated, substantially as described. 3. In a telephone system, the combination with a pair 0 telephone lines,of a cord circuit for making connection therewith for conversation, a line relay permanently connected with the line, two windings for said rela one in the circuit of each line conductor, 'a central source of current at the central oflice, an impedance 0011 between said source and one strand of the cord cir-.

ring a su cientlyl cuit, a third conductor at the central oflice, a cut-off relay permanently connected with said third'conductor, a supervisory signal in said third conductor associated with the cord circuit, and a low resistance path inparallel with the said conductor associatedwith the line, said supervisory signal receiving insufficient current for its operation 1 when said low resistance path is open, said path being closed by the contacts of said ine relay when the subscribers telephone is not in use, said impedance coil being substituted in the line for one of the windings of said line relay when a connection is established with the line, substantially as described.

"4. In a tele hone system, the combination with a pair 0 telephone lines, of a cord circuit for makin connection therewith for conversation, a ine relay permanently connected in the path of current to the substation, a source of current associated with the cord circuit, athird conductor in the cord circuit containing a supervisory signal perinanently connected with said source, a cooperating third conductor associated with the line having two parallel branches, a cut 7 off rela in one of said branches of. sufficiently igh resistance to prevent the operation of said signal and controlling contacts in the circuit ofthe line, the other of said branches being of sufliciently low resistance to permit the operation of the supervisory nal, and means associated with said line ay for closing said low resistance branch when the subscribers receiver is not. in use, substantiall as described. a

5. In ate e hone system, the combination with a pair o telephone lines, of a cord cirof said branches or sufficiently hig resistance to prevent the operation of said signal,

aving at the other ofsaid branches being of suffit-ion t ereof, said impedance coil being substituted in the line circuit for one wmdin of said line rela during conversation, an

means associate with said relay for closing low resistance to permitthe opera-J20 said low resistance branch when the con-" 'versation has terminated, substantially as described,

6. In a telephone system, the combination with a pair 0 telephone lines, "ofa cord circuit for making connection therewith for con- .station, and having one winding containing 'ing 'two parallel branches,

ficiently low resistance to permit th versation, aline relay permanently connected in the pathof current to the subin the circuit of each line conductor, a source of'current associated with the cord circuit, an im pedance coil connectedbetween one side of said source'and one strand of the cord circuit, a third conductor in the cord circuit a supervisory signal permanently connecte with third conductor associated with the v a cut-ofi relay in one of said branches of sufficiently sistance to prevent the operationof s' d si ml, the other of'said branches being of s 1' e operation thereof, a line si al for the line ha itscircuit normally'c osedat the contacts 0% said cut-off relay and normally open at the I coil be' nected' in the Ontacts of said line. relay; said impedance substituted in the line circuitfor one winding of said line rela duringconversation, and means associated with said relay for closing said low resistance branch when .the conversation has terminated, substantially as described.

. 7. Inatele hone'system, the combination with'a pair oi telephone lines, ofa cord circuit for makin connection therewith for conversatlon, a

ine relay permanently 'contion, and havmg'one winding in the circuit of'ieach line conductor, the circuit'of said wind s being completed thro h the normally fiosed contacts of the sai cut-01f relay, a'source of current associated with the cord circuit, an impedance coil connected between one side of said source and one strand of the cord circuit, a thirdconductor in the ervisory signal said source, a

cooperating third conductor associated with the line having two parallel branches, a cutoff relay in one of sai branches of sufiiciently h resistance to prevent the operation of said 'si nal, the other of said branches being of smh at the contacts of said said source, a coofirlsrating ehavpath of current to the substa-- ciently low resistance to permit the operation thereof, a line for the line tacts of said cut-ofi relay and normal] open hne relay, sai impedance coil being substituted in the line circuit for one of said line relay (1 conversation, and means associated wit for closing said low resistkfice saidrelay branch when the conversation has terminated, substantially as described.

8. In a telephone system, the combination with a telephone line, of a line relay, a cord circuit for making connection with the line for conversation, a source of current associated with the cord circuit, an'impedance connected between said source and a strand of the cord. circuit, a supervisory s' al in a local circuit of said source, a cut-o relay in the path of current through said supervisory signal, and means associated with said line re ay for rendering said signal inert during conversation, subtantiallyas' described.

9. In a telephone system, the combination with a tele hone line, of a central source of current, a between a pole of said source and a limb of said line, a cut-olf relay controlling normally closed contacts in the circuit of the other limb of said line, a cord circuit, a third conductor, a superviso signal for the cord circuit, said signal an the coil of said cut-01f relay bei connected in said third conductor, a pat in parallel with the windin of ceiving insufiicient current for its operation when the parallel path is open, said path being closed by contacts of said line relay when the subscriber s tele hone is not in use, substantially as described? sined by me at Chica 0, county of Cook, and tate of Illinois, in t e presence of two witnesses.

CHARLES s. WINSTON.

Witnesses:

O. O. BRADBURY, E. F. GRIER.

said supervisory signa ree relay permanently connected 

